The present invention also relates to a control program for carrying out such a method of operation, in a central unit of an automation system and in an automation system itself.
Automation systems, their central units, and also methods of operation and control programs for central units are general knowledge.
In the prior art, it may be that the control program comprises at least two subprograms, with only one of the subprograms being activated at a time and the central unit executing only the activated subprogram. One example of such a situation involves, by way of example, an automation system controlling an industrial technical process which can be divided into consecutively executable sub-processes.
In the prior art, the following procedures are known for controlling such an industrial technical process. The control program stored in the central unit comprises at least two subprograms. All of the subprograms are equivalent from the point of view of the central unit. In particular, the control program does not provide the central unit with prior knowledge of how many and what subprograms are active at what time.
In this case, the cycle time stipulated by the control program needs to have been determined to be of a length such that it is at least as long as the time which is required in order to execute all of the subprograms.
In this case, it is admittedly possible to change the subprograms dynamically. Since the dynamics of the control program are determined essentially by the cycle time, however, only relatively low dynamics can be provided.
Alternatively, it is known practice to create a separate control program for each subprogram. In this case, the cycle time for each subprogram may be individually chosen to be short enough for it to suffice just for executing the respective subprogram. However, changing from one subprogram to another subprogram requires that the execution of the subprogram currently being executed be interrupted, that the new subprogram to be executed be subsequently loaded into the central unit, and that the central unit be restarted.
It may also be conceivable to combine the subprograms into a common control program and to assign each subprogram a separate cycle time optimized for the respective subprogram. In this case, although the response of the controlled process would be as dynamic as possible, the varying cycle time would mean that a deterministic response would no longer be ensured.